By VETTAPHARMA reporter, 19th February 2026: Eli Lilly and Company announced positive topline results from the landmark Phase 3b TOGETHER-PsO clinical trial evaluating the concomitant use of Taltz (ixekizumab) and Zepbound (tirzepatide) compared with ixekizumab alone in adults with moderate-to-severe plaque psoriasis and obesity or overweight. The open-label trial showed that the combination therapy significantly outperformed Taltz monotherapy across multiple key endpoints, suggesting an integrated treatment approach may better address the dual burden of psoriasis and obesity.
The TOGETHER-PsO study enrolled 274 adults with moderate-to-severe plaque psoriasis and obesity or overweight plus at least one weight-related comorbidity. After 36 weeks of treatment, 27.1% of participants receiving both Taltz and Zepbound achieved complete skin clearance (PASI 100) and at least 10% body weight reduction, compared with 5.8% of those on ixekizumab alone (p < .001), meeting the trial’s primary endpoint.
In a key secondary endpoint, the combination therapy delivered a 40% relative increase in the proportion of patients achieving PASI 100 compared with ixekizumab alone (40.6% vs. 29.0%) (p < .05), further illustrating the potential benefits of addressing both inflammatory disease and excess weight concurrently.
Psoriasis and obesity share overlapping inflammatory and metabolic mechanisms. Roughly 61% of adults with psoriasis in the U.S. are also affected by obesity or overweight with at least one additional weight-related medical condition, highlighting the clinical relevance of a dual-targeted treatment strategy.
Safety and Adverse Events
Adverse events observed with the combination therapy were generally mild to moderate and consistent with established safety profiles of the individual drugs. The most common events (≥ 5%) in the combination arm included nausea, diarrhea, constipation, injection site reactions, dosing error, vomiting, and dizziness. In the Taltz monotherapy arm, the most frequent events were injection site reactions, dosing errors, and nasopharyngitis.
Broader Clinical Implications
Beyond skin outcomes, related data from other Phase 3b studies suggest that combining tirzepatide with ixekizumab may also benefit patients with psoriatic arthritis (PsA) and obesity. In a separate TOGETHER-PsA trial, approximately 31.7% of patients receiving the combination achieved both a 50% reduction in PsA disease activity and ≥10% weight loss at 36 weeks, compared with 0.8% on ixekizumab alone (p < .001).
Lilly plans to publish detailed results from the TOGETHER-PsO trial in a peer-reviewed journal and share the data with regulatory authorities.
Source credit:
- Eli Lilly and Company. (2026, Feb. 18). Lilly’s Taltz (ixekizumab) and Zepbound (tirzepatide) used together delivered superior efficacy in first-of-its-kind Phase 3b trial for adults with psoriasis and obesity or overweight [Press release]. Click here
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